The Fischer F-91 is a Surface Current Probe used for measuring the 'skin' current flowing in a surface. It is sensitive to the direction of flow by the positioning of the probe. The Fischer F-91 is typically used in conjunction with an analyser and cable.

Where would this be used? The Fischer F-91 Surface Current Probe can be used for Conducted Emissions testing. It can also be useful for fault finding and investigatory purposes.